Action-Domain-Responder - PHPNW14

The slides for my talk about the Action-Domain-Responder design pattern at PHP Northwest 2014. If you were at my talk, please rate it: https://joind.in/11806

The example code I used in this slide deck is also on github: https://github.com/tobiasgies/adr-phpnw14

Transcript

1. The Action-Domain-Responder
   Design Pattern
   

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2. Code's over here:
   https://github.com/tobiasgies/adr-phpnw14
   

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3. Design Pattern?
   

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4. Design Pattern!
   

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5. A look at MVC
   ●
   Separates concerns
   of desktop app
   ●
   Interactive
   environment
   ●
   Event-driven
   ●
   OLDER THAN ME!
   (Says the 23-year-old)
   

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6. A look at MVC
   Controller
   Model
   View
   

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7. Actually...
   Controller
   Model
   View
   Controller
   Model
   View
   Controller
   Model
   View
   Controller
   Model
   View
   Controller
   Model
   View
   Controller
   Model
   View
   Controller
   Model
   View
   

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8. MVC on the web
   Controller
   Model
   View
   SYSTEM
   BO
   UN
   DARY
   

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9. Let's refine this.
   

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10. Web-specific
    ●
    We are on a server
    ●
    In-memory desktop patterns won't help us
    ●
    Use existing ideas as a basis
    ●
    Refine towards better practices
    

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11. From Model to Domain
    ●
    Essentially identical responsibilities:
    – Communicate with data source
    – Encapsulate business rules
    ●
    Renamed to reflect more modern concepts:
    – Domain Logic
    – Domain Driven Design
    

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12. A controller does too much.
    ●
    Controller's methods:
    – indexAction
    – createAction
    – editAction
    – deleteAction
    – …
    ●
    Dependency Injection nightmare
    ●
    Single Responsibility Principle?!
    

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13. An action method does too much.
    ●
    An action method's job:
    – Make sense of input
    – Pass input to Model
    – Check model's results
    – Figure out which response to send
    – Prepare and return response
    – …
    ●
    Single Responsibility Principle?!
    

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14. From Controller to Action
    ●
    One class per Action
    ●
    Sharper focus:
    – Make sense of input
    – Pass input to Domain
    – Pass Domain's results to Responder
    

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15. A View is not enough
    ●
    A view's task:
    – Accept application data
    – Build output from data and templates
    ●
    View does not take care of:
    – Deciding which data type to output
    – Sending neccessary HTTP headers
    ●
    View is Response, we need a Responder
    

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16. From View to Responder
    ●
    Sends HTTP headers
    ●
    Assembles output
    ●
    Returns Response
    

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17. Components
    ●
    Domain: The logic to manipulate data and
    application state, based on your business rules.
    ●
    Responder: Handles everything connected to
    building an HTTP response. Headers, cookies,
    status codes and response content are built here.
    ●
    Action: Connects the Domain and Responder.
    Passes input data to Domain, passes Domain
    output to Responder.
    

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18. Enough talking,
    let's look at the code.
    

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19. class BlogController {
    private $request;
    private $response;
    private $model;
    private $view;
    public function __construct(
    Request $request,
    Response $response,
    BlogRepository $model,
    TemplateSystem $view
    ) { /* ... */ }
    public function indexAction() { /* ... */ }
    public function createAction() {
    if ($this->request->isPost()) {
    $data = $this->request->getParameters(Request::SOURCE_POST);
    $post = $this->model->createPost($data);
    if ($post->isValid()) {
    $post->save();
    $this->response->redirect('/blog/edit/' . $post->getId());
    } else {
    $this->response->setContent(
    $this->view->render('create.tpl', array('post' => $post))
    );
    }
    } else {
    $this->response->setContent(
    $this->view->render('create.tpl', array('blog' => $this->model->getDefault()))
    );
    }
    }
    public function editAction() { /* ... */ }
    public function deleteAction() { /* ... */ }
    }
    

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20. public function createAction() {
    if ($this->request->isPost()) {
    $data = $this->request->getParameters(Request::SOURCE_POST);
    $post = $this->model->createPost($data);
    if ($post->isValid()) {
    $post->save();
    $this->response->redirect('/blog/edit/' . $post->getId());
    } else {
    $this->response->setContent(
    $this->view->render(
    'create.tpl',
    array('post' => $post)
    )
    );
    }
    } else {
    $this->response->setContent(
    $this->view->render(
    'create.tpl',
    array('blog' => $this->model->getDefault())
    )
    );
    }
    }
    

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21. Let's refactor this.
    

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22. class BlogCreateAction {
    private $request;
    private $domain;
    private $responder;
    public function __construct(
    Request $request,
    BlogRepository $domain,
    BlogCreateResponder $responder
    ) { /* ... */ }
    public function __invoke() {
    if ($this->request->isPost()) {
    $data = $this->request->getParameters(
    Request::SOURCE_POST
    );
    $post = $this->domain->createPost($data);
    if ($post->isValid()) {
    $post->save();
    }
    } else {
    $post = $this->domain->getDefault();
    }
    $this->responder->__invoke($post);
    }
    }
    

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23. class BlogCreateResponder {
    private $response;
    private $templateSystem;
    public function __construct(
    Response $response, TemplateSystem $templateSystem
    ) { /* ... */ }
    public function __invoke(BlogPost $post) {
    if (!empty($post->getId())) {
    $this->response->redirect('/blog/edit/' . $post->getId());
    } else {
    $this->response->setContent(
    $this->templateSystem->render(
    'create.tpl', array('post' => $post)
    )
    );
    }
    }
    }
    

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24. Can we clean up further?
    

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25. class BlogAddAction {
    private $domain;
    private $responder;
    public function __construct(
    BlogRepository $domain,
    BlogCreateResponder $responder
    ) { /* ... */ }
    public function __invoke() {
    $post = $this->domain->getDefault();
    $this->responder->__invoke($post);
    }
    }
    

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26. class BlogCreateAction {
    private $request;
    private $domain;
    private $responder;
    public function __construct(
    Request $request,
    BlogRepository $domain,
    BlogCreateResponder $responder
    ) { /* ... */ }
    public function __invoke() {
    try {
    $data = $this->request->getParameters(
    Request::SOURCE_POST
    );
    $post = $this->domain->createPost($data);
    } catch (BlogException $ex) {
    $post = $this->domain->getDefault();
    }
    $this->responder->__invoke($post);
    }
    }
    

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27. class BlogCreateResponder {
    private $response;
    private $templateSystem;
    public function __construct(
    Response $response, TemplateSystem $templateSystem
    ) { /* ... */ }
    public function __invoke(BlogPost $post) {
    if (!empty($post->getId())) {
    $this->response->redirect('/blog/edit/' . $post->getId());
    } else {
    $this->response->setContent(
    $this->templateSystem->render(
    'create.tpl', array('post' => $post)
    )
    );
    }
    }
    }
    

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28. Action-Domain-Responder
    

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29. Any questions?
    

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30. Thank you!
    tobias@tobiasgies.de - @tobiasgies
    https://joind.in/11806
    

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